Question

Ice formed over lakes has

• A. Very high thermal conductivity and helps in further ice formation
• B. Very low conductivity and retards further formation of ice
• C. It permits quick convection and retards further formation of ice
• D. It is very good rediator

Answer 1

The correct option is B Very low conductivity and retards further formation of ice

It is the anomalous or unusual expansion of water which causes ice to form a thin layer over a lake. It is really helpful for the aquatic life in cold countries or when temperature falls down. Anomalous expansion of water refers to that characteristic of water which makes it expand when cooled from 4℃ to 0℃. Due to this reason, water has maximum density at 4℃. Since water at 4℃ is denser than ice at 0℃, so ice goes to the surface of water at forms a layer of ice. Once the layer is formed it prevents further cooling of the water below the ice since ice is a bad conductor of heat.